The primary objective as elaborated in this proposal is to gain insight into the molecular mechanisms responsible for membrane transport in red blood cells. There is evidence that the membrane may contain more than one type of cation pump and that certain of the so-called passive movements of cations appear to depend upon metabolism. The work is oriented toward establishing the energy relationships and coupling mechanisms between transport and metabolisms. It is planned to correlate with the flux measurements analyses and separate assay of various glycolytic intermediates in an attempt to identify specific substrates underlying the different metabolically coupled transports. These studies will necessarily be carried out using various ionic environments, inhibitors and metabolic conditions. It is also planned to study the binding characteristics of cardiac glycosides, K, Cs, nucleotides and pump specific fluorescent probes to intact membranes and to membrane components in an effort to define more precisely the molecular events associated with membrane transport.